grep: stop leaking line strings with -f

When reading patterns from a file, we pass the lines as allocated string
buffers to append_grep_pat() and never free them.  That's not a problem
because they are needed until the program ends anyway.

However, now that the function duplicates the pattern string, we can
reuse the strbuf after calling that function.  This simplifies the code
a bit and plugs a minor memory leak.

Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
ident: split setup_ident into separate functions

This function sets up the default name, email, and date, and
is not publicly available. Let's split it into three public
functions so that callers can get just the parts they need.

While we're at it, let's change the interface to simple
accessors. The original function was called only by fmt_ident,
and contained logic for "if we already have some other
value, don't load the default" which properly belongs in
fmt_ident.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
http-push: do not access git_default_email directly

By calling the ident_default_email accessor, we can be sure
that the default value is actually filled-in.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
fmt-merge-msg: don't use static buffer in record_person

The record_person function just parses out the "name" field
of the person line in a commit and adds it to a string_list.
The only reason we need an extra buffer is that the
string_list functions require a NUL-terminated string.

Instead of the static buffer, we can just allocate a
temporary NUL-terminated copy. In addition to removing a
useless limit, this removes the only user of MAX_GITNAME
outside of ident.c.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
move identity config parsing to ident.c

There's no reason for this to be in config, except that once
upon a time all of the config parsing was there. It makes
more sense to keep the ident code together.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
move git_default_* variables to ident.c

There's no reason anybody outside of ident.c should access
these directly (they should use the new accessors which make
sure the variables are initialized), so we can make them
file-scope statics.

While we're at it, move user_ident_explicitly_given into
ident.c; while still globally visible, it makes more sense
to reside with the ident code.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
ident: trim trailing newline from /etc/mailname

We use fgets to read the /etc/mailname file, which means we
will typically end up with an extra newline in our
git_default_email. Most of the time this doesn't matter, as
fmt_ident will skip it as cruft, but there is one code path
that accesses it directly (in http-push.c:lock_remote).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
format-patch: use default email for generating message ids

We try to generate a sane message id for cover letters and
threading by appending some changing bits to the front of
the user's email address. The current code parses the email
out of the results of git_committer_info, but we can do this
much more easily by just calling ident_default_email
ourselves.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
fmt_ident: drop IDENT_WARN_ON_NO_NAME code

There are no more callers who want this, so we can drop it.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
ident: don't write fallback username into git_default_name

The fmt_ident function gets a flag that tells us whether to
die if the name field is blank. If it is blank and we don't
die, then we fall back to the username from the passwd file.

The current code writes the value into git_default_name.
However, that's not necessarily correct, as the empty value
might have come from git_default_name, or it might have been
passed in.  This leads to two potential problems:

  1. If we are overriding an empty name in the passed-in
     value, then we may be overwriting a perfectly good name
     (from gitconfig or gecos) in the git_default_name
     buffer. Later calls to fmt_ident will end up using the
     fallback name, even though a better name was available.

  2. If we override an empty gecos name, we end up with the
     fallback name in git_default_name. A later call that
     uses IDENT_ERROR_ON_NO_NAME will see the fallback name
     and think that it is a good name, instead of producing
     an error. In other words, a blank gecos name would
     cause an error with this code:

       git_committer_info(IDENT_ERROR_ON_NO_NAME);

     but not this:

       git_committer_info(0);
       git_committer_info(IDENT_ERROR_ON_NO_NAME);

     because in the latter case, the first call has polluted
     the name buffer.

Instead, let's make the fallback a per-invocation variable.
We can just use the pw->pw_name string directly, since it
only needs to persist through the rest of the function (and
we don't do any other getpwent calls).

Note that while this solves (1) for future invocations of
fmt_indent, the current invocation might use the fallback
when it could in theory load a better value from
git_default_name. However, by not passing
IDENT_ERROR_ON_NO_NAME, the caller is indicating that it
does not care too much about the name, anyway, so we don't
bother; this is primarily about protecting future callers
who do care.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
drop length limitations on gecos-derived names and emails

When we pull the user's name from the GECOS field of the
passwd file (or generate an email address based on their
username and hostname), we put the result into a
static buffer. While it's extremely unlikely that anybody
ever hit these limits (after all, in such a case their
parents must have hated them), we still had to deal with the
error cases in our code.

Converting these static buffers to strbufs lets us simplify
the code and drop some error messages from the documentation
that have confused some users.

The conversion is mostly mechanical: replace string copies
with strbuf equivalents, and access the strbuf.buf directly.
There are a few exceptions:

  - copy_gecos and copy_email are the big winners in code
    reduction (since they no longer have to manage the
    string length manually)

  - git_ident_config wants to replace old versions of
    the default name (e.g., if we read the config multiple
    times), so it must reset+add to the strbuf instead of
    just adding

Note that there is still one length limitation: the
gethostname interface requires us to provide a static
buffer, so we arbitrarily choose 1024 bytes for the
hostname.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
ident: report passwd errors with a more friendly message

When getpwuid fails, we give a cute but cryptic message.
While it makes sense if you know that getpwuid or identity
functions are being called, this code is triggered behind
the scenes by quite a few git commands these days (e.g.,
receive-pack on a remote server might use it for a reflog;
the current message is hard to distinguish from an
authentication error).  Let's switch to something that gives
a little more context.

While we're at it, we can factor out all of the
cut-and-pastes of the "you don't exist" message into a
wrapper function. Rather than provide xgetpwuid, let's make
it even more specific to just getting the passwd entry for
the current uid. That's the only way we use getpwuid anyway,
and it lets us make an even more specific error message.

The current message also fails to mention errno. While the
usual cause for getpwuid failing is that the user does not
exist, mentioning errno makes it easier to diagnose these
problems.  Note that POSIX specifies that errno remain
untouched if the passwd entry does not exist (but will be
set on actual errors), whereas some systems will return
ENOENT or similar for a missing entry. We handle both cases
in our wrapper.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
ident: use full dns names to generate email addresses

When we construct an email address from the username and
hostname, we generate the host part of the email with this
procedure:

  1. add the result of gethostname

  2. if it has a dot, ok, it's fully qualified

  3. if not, then look up the unqualified hostname via
     gethostbyname; take the domain name of the result and
     append it to the hostname

Step 3 can actually produce a bogus result, as the name
returned by gethostbyname may not be related to the hostname
we fed it (e.g., consider a machine "foo" with names
"foo.one.example.com" and "bar.two.example.com"; we may have
the latter returned and generate the bogus name
"foo.two.example.com").

This patch simply uses the full hostname returned by
gethostbyname. In the common case that the first part is the
same as the unqualified hostname, the behavior is identical.
And in the case that it is not the same, we are much more
likely to be generating a valid name.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
ident: use a dynamic strbuf in fmt_ident

Now that we accept arbitrary-sized names and email
addresses, the only remaining limit is in the actual
formatting of the names into a buffer. The current limit is
1000 characters, which is not likely to be reached, but
using a strbuf is one less error condition we have to worry
about.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
ident: trim whitespace from default name/email

Usually these values get fed to fmt_ident, which will trim
any cruft anyway, but there are a few code paths which use
them directly. Let's clean them up for the benefit of those
callers. Furthermore, fmt_ident will look at the pre-trimmed
value and decide whether to invoke ERROR_ON_NO_NAME; this
check can be fooled by a name consisting only of spaces.

Note that we only bother to clean up when we are pulling the
information from gecos or from system files. Any other value
comes from a config file, where we will have cleaned up
accidental whitespace already.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
format-patch: refactor get_patch_filename

The get_patch_filename function expects a commit argument
and uses it to get the sanitized subject line when making a
patch filename. However, we also want to use this same
function for the cover letter, which does not have a commit
object. The current solution is to create a fake commit with
the subject "cover letter". Instead, let's make the
get_patch_filename interface more flexibile, and allow
passing a direct subject.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
fix off-by-one error in split_ident_line

Commit 4b340cf split the logic to parse an ident line out of
pretty.c's format_person_part. But in doing so, it
accidentally introduced an off-by-one error that caused it
to think that single-character names were invalid.

This manifested itself as the "%an" format failing to show
anything at all for a single-character name.

Reported-by: Brian Turner <bturner@atlassian.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
pretty: avoid buffer overflow in format_person_part

When we parse the name and email from a commit to
pretty-print them, we usually can just put the result
directly into our strbuf result. However, if we are going to
use the mailmap, then we must first copy them into a
NUL-terminated buffer to feed to the mailmap machinery.

We did so by using strlcpy into a static buffer, but we used
it wrong. We fed it the length of the substring we wanted to
copy, but never checked that that length was less than the
size of the destination buffer.

The simplest fix is to just use snprintf to copy the
substring properly while still respecting the destination
buffer's size. It might seem like replacing the static
buffer with a strbuf would help, but we need to feed a
static buffer to the mailmap machinery anyway, so there's
not much benefit to handling arbitrary sizes.

A more ideal solution would be for mailmap to grow an
interface that:

  1. Takes a pointer and length combination, instead of
     assuming a NUL-terminated string.

  2. Returns a pointer to the mailmap's allocated string,
     rather than copying it into the buffer.

Then we could avoid the need for an extra buffer entirely.
However, doing this would involve a lot of refactoring of
mailmap and of string_list (which mailmap uses to store the
map itself). For now, let's do the simplest thing to fix the
bug.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
avoid segfault when reading header of malformed commits

If a commit object has a header line at the end of the
buffer that is missing its newline (or if it appears so
because the content on the header line contains a stray
NUL), then git will segfault.

Interestingly, this case is explicitly handled and we do
correctly scan the final line for the header we are looking
for. But if we don't find it, we will dereference NULL while
trying to look at the next line.

Git will never generate such a commit, but it's good to be
defensive. We could die() in such a case, but since it's
easy enough to handle it gracefully, let's just issue a
warning and continue (so you could still view such a commit
with "git show", though you might be missing headers after
the NUL).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
cmd_fetch_pack(): declare dest to be const

There is no need for it to be non-const, and this avoids the need
for casting away the constness of an argv element.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>